Pseudorabies virus in wild swine: a global perspective

Abstract

Suid herpesvirus 1 (SuHV1, syn. Aujeszky's disease virus [ADV] or pseudorabies virus [PrV]), which belongs to the family Herpesviridae, subfamily Alphaherpesvirinae, genus Varicellovirus is the causative agent of Aujeszky's disease (AD, pseudorabies), a notifiable disease, that causes substantial economic losses to the swine industry in countries, where AD is present. Members of the family Suidae (true pigs) are the only natural hosts for PrV, although the virus can infect numerous other mammals including ruminants, carnivores and rodents. Despite the tremendous progress that has been made in controlling and eliminating PrV in domestic pigs, there is mounting evidence that PrV infections are more widespread in wild swine across the world than originally thought. Unfortunately, our understanding of the extent of PrV infections in these wild populations and of the threat to domestic swine is still fragmentary. This review aims at giving a global perspective on PrV infections in wild swine by scrutinizing the current state of knowledge concerning (i) the global occurrence of PrV infections in free-living populations of wild swine, e.g., wild boar and feral swine, (ii) the molecular characterization of wild swine PrV, (iii) infection characteristics of PrV in populations of wild swine, (iv) the risk of spillover infections to domestic pigs, (v) potential risk-mitigating measures, focusing on further research needs.

SEROLOGIC, MOLECULAR, AND PATHOLOGIC SURVEY OF PSEUDORABIES VIRUS INFECTION IN HUNTED WILD BOARS (SUS SCROFA) IN ITALY

“…Despite the small sample size, our results confirmed that PrV infection is endemic in wild-boar populations in the study area, with antibody prevalence similar to that previously reported in Italy (Lari et al 2006) and Europe (Mü ller et al 2011). Eight years prior to our study, similar epidemiologic studies in the area had comparable results, demonstrating that PrV infection persists in wild boar populations (Corn et al 2004).…”

“…Several studies and field observations indicate that PrV infection of wild boars results in low pathogenicity, indicating that the virus is attenuated in wild boars (Mü ller et al 2011). Studies carried out with the use of PrV isolates from the US and East Germany produced mild clinical symptoms in experimentally infected wild boars and domestic pigs Mü ller et al 2001).…”

“…Type I is predominantly found in the US and Central Europe; types II and III circulate in Central and Northern Europe, respectively; type IV is restricted to Asia (Mü ller et al 2011). With the use of this technique, a comprehensive study of European PrV isolates from wild boar demonstrated that all but one were genotype I .…”

“…Nevertheless, experimental studies suggest a potential risk; thus, infected wild swine can shed sufficient virus to cause infection Mü ller et al 1998b). Based on available data (Mü ller et al 2011), there is reason to believe that PrV infection in wild boar populations will increase. Although there has been much progress toward elimination of pseudorabies in domestic pigs, the vast range of wild boar infected with PrV is a growing concern in North America and Europe, particularly for ''backyard'' holding facilities or outdoor swine farms.…”

“…Pseudorabies virus circulates in domestic swine and wild boar (Sus scrofa) populations in several countries (Mü ller et al 2011). The role of wild boars in the epidemiology of the disease is unclear because virus isolation from wild boars has been rarely reported .…”